I think it would be safe to assume the aircraft were at different levels...now I know you are going to say "but they looked like they were very close..."
In reality they were probably at least 1000' apart and probably more likely 2000' (1 at 320 and 1 at 340 so 1 at 330 can go the other way).
Your eyes can play tricks on you...I mean look at Popstars for instance
cos I just noticed you said westbound - of course we would have to call for the FL320 because of the FLA... oh dont worry